USB Repeater Power-State Switching for Low-Idle Signal Links
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Solution Overview
Problem
Existing USB repeaters face challenges in reducing power consumption during the normal active state (L0 state) while maintaining signal quality over long transmission distances.
Innovation Solution
A USB repeater device with a control circuit that dynamically adjusts operation modes based on signal activity, switching to power-saving states when ports are idle, and active states when transactions are imminent, using repeaters in standby or power-off modes to conserve power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the repeater operates in the L0 state to propagate transaction signals in real time, then signal transmission quality is maintained, but power consumption increases
Solution Approach 1:
The repeater dynamically switches between L0, L1, L2, and L3 states based on USB transaction activity detection. The control circuit monitors the USB bus state and transitions the repeater to appropriate power management states, enabling adaptive power consumption while maintaining signal quality when needed
Solution Approach 2:
The repeater changes its operational parameters by transitioning between different LPM states (L0, L1, L2, L3), each with distinct power consumption characteristics. This allows the system to optimize the balance between power savings and signal transmission capability based on actual USB transaction requirements
2Use of energy by moving object
If the repeater enters L1, L2, or L3 state to save power, then power consumption is reduced, but signal transmission capability is compromised
Solution Approach 1:
The control circuit detects USB transaction start signals in advance and proactively transitions the repeater from low-power states (L1, L2, L3) back to the L0 state before actual data transmission begins. This preliminary detection and transition mechanism ensures the repeater is ready to transmit signals immediately when needed, maintaining reliability while maximizing power savings during idle periods
3Reliability
If the repeater remains in L0 state continuously, then real-time signal propagation is ensured, but power savings are limited
Solution Approach 1:
The repeater implements periodic monitoring of USB bus activity and transitions between power management states accordingly. During idle periods, the repeater enters low-power states (L1, L2, or L3), and upon detecting transaction activity, it transitions back to L0 state. This periodic switching pattern reduces average power consumption while maintaining real-time signal propagation capability when USB transactions occur
Data Source
AI summary
The USB repeater device includes a USB-host-side port, a USB-device-side port, a first repeater, a second repeater, and a control circuit. The USB-host-side port is coupled to an input terminal of the first repeater and an output terminal of the second repeater. The USB-device-side port is coupled to an output terminal of the first repeater and an input terminal of the second repeater. The control circuit detects the signal of the USB-host-side port and the signal of the USB-device-side port to dynamically determine an operation mode. When the operation mode is a waiting transaction-start mode, the first repeater operates in a standby state, and the second repeater operates in a power-off state. When the operation mode is a waiting transaction-finish mode, the first repeater and the second repeater transmit transactions between the USB-host-side port and the USB-device-side port.